Artificial thread



' Patented Feb. 21,193

- UNITED STAT S PATENT [oFFIcE-Q WALTER SEIIDEL AND ALBERT ERNECKE, OF DORMAGEN, GERMANY, ASSIGNORS .130

m'rrrromr. mm

1T0 Drawing. Application filed 'April 5, 1929, Serial No. 852,906, and in Germany April 12,1928.

propionic acids and stretching the threads from about 50% .to about 400% of their length. The concentration and the temperature'of'the diluted acids used in our process may be varied, but care must be taken that the threads are not caused tostick together; the concentration somewhat depends on the temperature at which the process is carried out, generally we work with an acid having a concentration between about 30% and about and a temperature from about 15 to about 30 (3.; the lower the temperature the higher must be the concentration of the acid. The threads after having been stretched-according to our process are washed with water until free from acid and dried; advantageously the threads are kept in tension during the washing and drying process by. attaching a weight thereto. As in stretching the threads the liquid is pressed out, care must be taken that during the whole.

stretching process diluted acid is present, for example by irrigation with said diluted acids. The best results are-obtained in our process if the removing of the acid is performed in stages, that will say, the stretching is not completely performed with an acid of ahout 30 to about 45%,but, after a partial stretching the concentration of the acid, the

- threads are irrigated with, is diminishedto about 25%,- after a further stretching the concentration is diminished to about 20%;

- the stretching is completed with an acid of about 10% strength.

Our process may be carried out either directly after the spinning process by treating the single threads according to'our new maintained by appendin process; but generally we use for the pur- FRANKFORT-ON-THE-m,

pose-of our invention cellulose acetate silk in form of ropes, the threads of which may be twisted or untwisted. I

Artlficialthreads prepared from cellulose acetate according to the dry spinning process have an average tensile strength of 100 to 120 grams per 100 deniers, sometimes up to 150 grams. By treating cellulose acetate threads accordin to our new process their tensile strength 1s highly increased and the diameter of the thread is diminished. The invention is illustrated by the followmg examples, without being limited thereto: Ewample l.-A rope of cellulose acetate silk prepared according to the dry spinning process having in the dry state .a tensile strength of 100 grams per 100 deniers and in the moist state a tensile strength of 50 grains per 100 deniers and the threads having a titer of 7 deniers, is impregnated with a 40% acetic acid of about 18 C. and extended by slowly stretching to three times its length. During the stretching the rope is irrigated with 40% acetic acid the concentration of which is by and by decreased; when the stretching is complete, the rope is washed with water and dried, a tension thereby being a weight to the rope. The threads thus 0 tained have in the dry state a tensile strength of more than 240 grams per-100 deniers, in the moist state a tensile strength of more than 150 grams per 100 deniers, the titer of the thread is 2.2 deniers.

Example 2.--A rope of cellulose acetate silk is impregnated with a 35% aqueous formic acid of 20 (3., and is then stretched toabout 200%; then the acid is removed in stages while maintaining the tension of the threads; the acetate silk is washed and dried as described in Exam 1e 1. It has the same properties as that of xample 1.

We'claim: 1. The process which comprises impregnating artificial silk which has been prepared from cellulose acetate according to the dry spinning process with an aqueous solution of a fatty acid of the group consisting of formic,

acetic; and propionic'acids :of 30 to 45% strength and having a temperature from 15 to 30 C. and stretching the artificial silk from to 400% its length, washing and drying the same.

2. The process which comprises impregnating artificial silk which has been prepared from cellulose acetate according to the dry spinning processwith an aqueous solution of a fatty acid of the group consisting of formic, acetic, and propionic acids of 30 to 45% stren h and havin a temperature from 15 to 30 and stretching the artificial silk from-50 to 400% its len th, removin the acid in stages and drying t e artificial Sllk.

3. The process which comprises impregnating artificial silk which has been prepared from cellulose acetate according to the dry spinning process with an aqueous acetic acid of about 40% strength and having a temperature from 15 to 30 C. and stretching the artificial silk from 50 to 400% its length, washing and drying the same. v

. 4. The rocess which comprises impregnating artificial silk which has been prepared from cellulose acetate according to the dry spinning process with an aqueous acetic acid of 40% strength and having a temperature from 15 to 30 C. and stretchmg the artificial silk from 50 to 400% its length, removing thlek acid in stages and drying the artificial s1 5.-The process which comprises impregnating a rope of artificial silk which has been prepared from cellulose acetate according to the dry spinning process with an aqueous solution of a fatty acid of the group consisting of formic, acetic, and propionic acids of 30 to 45% strength and having a temperature from 15 to 30 C. and stretching the rope from 50 to 400% its length, washing and drying the same.

6. The process which nating a rope of artificial silk which has been prepared from cellulose acetate according to the dry s inning process with an aqueous solution 0? a fatty acid of the group consisting of formic, acetic, and propionic acids of 30 to 45% strength and having a temperature from 15 to 30 C. and stretching the rope from 50 to 400% its length, removing the acid in stages and drying the rope.

7. The process which comprises impregnating a rope of artificial silk which has been prepared from cellulose acetate according to the dry spinning process with an aqueous acetic acid of 40% strength and having a temperature of about 18 C. and stretching the rope from 50 to 400% its length, washing and drying the same.

8. The process which comprises impreg nating a rope of artificial silk which has been prepared from cellulose acetate according to the dry spinning process with an aqueousacetic acid of 40% strength and having a temperature of about 18 and stretching comprises impregthe rope from 50 to 400% its length, removing the acid in stages and drying the artificlal silk.

In testimony whereof we have hereunto set our hands.

WALTER SEIDEL. [L. s.% ALBERT ERNECKE. [L. s. 

